1 /* 2 * Copyright (C) 2013 Square, Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package com.squareup.okhttp; 17 18 import com.squareup.okhttp.Call.AsyncCall; 19 import com.squareup.okhttp.internal.Util; 20 import com.squareup.okhttp.internal.http.HttpEngine; 21 import java.util.ArrayDeque; 22 import java.util.Deque; 23 import java.util.Iterator; 24 import java.util.concurrent.ExecutorService; 25 import java.util.concurrent.SynchronousQueue; 26 import java.util.concurrent.ThreadPoolExecutor; 27 import java.util.concurrent.TimeUnit; 28 29 /** 30 * Policy on when async requests are executed. 31 * 32 * <p>Each dispatcher uses an {@link ExecutorService} to run calls internally. If you 33 * supply your own executor, it should be able to run {@linkplain #getMaxRequests the 34 * configured maximum} number of calls concurrently. 35 */ 36 public final class Dispatcher { 37 private int maxRequests = 64; 38 private int maxRequestsPerHost = 5; 39 40 /** Executes calls. Created lazily. */ 41 private ExecutorService executorService; 42 43 /** Ready calls in the order they'll be run. */ 44 private final Deque<AsyncCall> readyCalls = new ArrayDeque<>(); 45 46 /** Running calls. Includes canceled calls that haven't finished yet. */ 47 private final Deque<AsyncCall> runningCalls = new ArrayDeque<>(); 48 49 /** In-flight synchronous calls. Includes canceled calls that haven't finished yet. */ 50 private final Deque<Call> executedCalls = new ArrayDeque<>(); 51 52 public Dispatcher(ExecutorService executorService) { 53 this.executorService = executorService; 54 } 55 56 public Dispatcher() { 57 } 58 59 public synchronized ExecutorService getExecutorService() { 60 if (executorService == null) { 61 executorService = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 60, TimeUnit.SECONDS, 62 new SynchronousQueue<Runnable>(), Util.threadFactory("OkHttp Dispatcher", false)); 63 } 64 return executorService; 65 } 66 67 /** 68 * Set the maximum number of requests to execute concurrently. Above this 69 * requests queue in memory, waiting for the running calls to complete. 70 * 71 * <p>If more than {@code maxRequests} requests are in flight when this is 72 * invoked, those requests will remain in flight. 73 */ 74 public synchronized void setMaxRequests(int maxRequests) { 75 if (maxRequests < 1) { 76 throw new IllegalArgumentException("max < 1: " + maxRequests); 77 } 78 this.maxRequests = maxRequests; 79 promoteCalls(); 80 } 81 82 public synchronized int getMaxRequests() { 83 return maxRequests; 84 } 85 86 /** 87 * Set the maximum number of requests for each host to execute concurrently. 88 * This limits requests by the URL's host name. Note that concurrent requests 89 * to a single IP address may still exceed this limit: multiple hostnames may 90 * share an IP address or be routed through the same HTTP proxy. 91 * 92 * <p>If more than {@code maxRequestsPerHost} requests are in flight when this 93 * is invoked, those requests will remain in flight. 94 */ 95 public synchronized void setMaxRequestsPerHost(int maxRequestsPerHost) { 96 if (maxRequestsPerHost < 1) { 97 throw new IllegalArgumentException("max < 1: " + maxRequestsPerHost); 98 } 99 this.maxRequestsPerHost = maxRequestsPerHost; 100 promoteCalls(); 101 } 102 103 public synchronized int getMaxRequestsPerHost() { 104 return maxRequestsPerHost; 105 } 106 107 synchronized void enqueue(AsyncCall call) { 108 if (runningCalls.size() < maxRequests && runningCallsForHost(call) < maxRequestsPerHost) { 109 runningCalls.add(call); 110 getExecutorService().execute(call); 111 } else { 112 readyCalls.add(call); 113 } 114 } 115 116 /** Cancel all calls with the tag {@code tag}. */ 117 public synchronized void cancel(Object tag) { 118 for (AsyncCall call : readyCalls) { 119 if (Util.equal(tag, call.tag())) { 120 call.cancel(); 121 } 122 } 123 124 for (AsyncCall call : runningCalls) { 125 if (Util.equal(tag, call.tag())) { 126 call.get().canceled = true; 127 HttpEngine engine = call.get().engine; 128 if (engine != null) engine.cancel(); 129 } 130 } 131 132 for (Call call : executedCalls) { 133 if (Util.equal(tag, call.tag())) { 134 call.cancel(); 135 } 136 } 137 } 138 139 /** Used by {@code AsyncCall#run} to signal completion. */ 140 synchronized void finished(AsyncCall call) { 141 if (!runningCalls.remove(call)) throw new AssertionError("AsyncCall wasn't running!"); 142 promoteCalls(); 143 } 144 145 private void promoteCalls() { 146 if (runningCalls.size() >= maxRequests) return; // Already running max capacity. 147 if (readyCalls.isEmpty()) return; // No ready calls to promote. 148 149 for (Iterator<AsyncCall> i = readyCalls.iterator(); i.hasNext(); ) { 150 AsyncCall call = i.next(); 151 152 if (runningCallsForHost(call) < maxRequestsPerHost) { 153 i.remove(); 154 runningCalls.add(call); 155 getExecutorService().execute(call); 156 } 157 158 if (runningCalls.size() >= maxRequests) return; // Reached max capacity. 159 } 160 } 161 162 /** Returns the number of running calls that share a host with {@code call}. */ 163 private int runningCallsForHost(AsyncCall call) { 164 int result = 0; 165 for (AsyncCall c : runningCalls) { 166 if (c.host().equals(call.host())) result++; 167 } 168 return result; 169 } 170 171 /** Used by {@code Call#execute} to signal it is in-flight. */ 172 synchronized void executed(Call call) { 173 executedCalls.add(call); 174 } 175 176 /** Used by {@code Call#execute} to signal completion. */ 177 synchronized void finished(Call call) { 178 if (!executedCalls.remove(call)) throw new AssertionError("Call wasn't in-flight!"); 179 } 180 181 public synchronized int getRunningCallCount() { 182 return runningCalls.size(); 183 } 184 185 public synchronized int getQueuedCallCount() { 186 return readyCalls.size(); 187 } 188 } 189